Problems with 3.0

Having some trouble with my invoicing since the new version went live? I can't mark any of my invoices as paid, it gives me the option to 'save' and loads after I press it, but the invoice remained in 'sent' form. Also, I noticed that I can't delete amounts off the total of an invoice. I tried to reshuffle the expenses on one in a way that would keep the total the same, but it doubled it. The only way I could manage was to delete the invoice and start anew. Seems like there are some bugs, but I'm not sure